Does More Sweat Mean a Better Workout?

Written by Robert J. Davis, Ph.D. on July 31, 2017

The sweatiest workouts can feel like the hardest workouts. Surely walking out of a hot yoga class or a steamy Spin session completely drenched means you got a good workout, right? Well, not exactly. How much you sweat doesn’t necessarily correlate with how intense your workout is or how many calories you burn. Here’s the deal.

Why Do We Sweat?

When your body temperature rises, your eccrine glands secrete sweat, and the evaporation of moisture from your skin helps you cool down. (Of course, sweating can occur for other reasons, such as stress or fear. Awkward first date? That type of sweat comes from the apocrine glands, which are located mainly in the underarm and groin.)

How much we sweat during exercise is due to a number of factors, including gender (men tend to sweat more than women) and age (younger people sweat more than older people), as well as genetics, temperature, and humidity.Weight plays a role as well: Larger people tend to sweat more because their bodies generate more heat.

Another contributor is fitness level. Surprisingly, fit people tend to sweat more than those who are less fit. Research suggests that as your fitness level improves, your body’s heat-regulating system kicks in sooner, cooling you down faster and allowing you to work harder, which translates to a lot more sweat.

And don’t be misled by the loss of a few pounds after a super sweaty workout. This is simply water weight you gain back when you rehydrate and doesn’t necessarily mean you’ve burned lots of calories.

On the flip side, don’t assume a low-sweat workout means you aren’t working hard enough or burning enough calories. It could be that your sweat is evaporating quickly, because you’re exercising in air-conditioning, near a fan, or outdoors on a windy day. Or maybe you just don’t sweat much in general.

How to Stay Dry

Wearing clothing made of synthetic fabrics such as polyester or Lycra can help you feel less sweaty. These pull (or wick) sweat from your skin to the outer layers of the clothes, where the moisture evaporates. Cotton, on the other hand, absorbs moisture but doesn’t promote evaporation. As a result, your shirt or other clothing can feel soaked and heavy during and after a workout. Ick.

A drawback of polyester is that it tends to stink more than cotton after exercise. In one study, researchers collected the sweaty shirts of 26 subjects after an hour of intensive spinning. The next day, trained sniffers determined the polyester shirts smelled worse than the cotton ones. (It’s unclear who exactly agreed to do this job or why.) Micrococci, a type of bacteria that break down sweat and cause unpleasant odor, grew only on the polyester garments. That’s important because sweat itself is generally odor free; it’s the combination of sweat and certain bacteria that literally raises a stink.

You can find odor-resistant synthetic fabrics, which are treated with various antibacterial compounds. Among the most prevalent are silver (like Lululemon’s Silverscent technology) and gold (like Rhone’s Goldfusion technology), typically applied in tiny amounts known as nanoparticles. But some research suggests silver-treated clothing may not work as well to reduce bacteria and odor. What’s more, a significant amount of the silver (or gold) may come out in the wash, reducing the effectiveness of the garments and potentially harming the environment.

The Bottom Line

Unfortunately for hot yogis and tropical climate dwellers, sweat is not a sign of intensity. Perspiration rate is personal and highly affected by other factors such as fitness level, heat, humidity, weight, and even age and gender. No matter how much you sweat, be sure to drink enough H20 to replace the water you lose.